Ink jet printers generally use an array of jets, which may also be referred to as drop emitters or nozzles. As the printing surface passes the array, or the array passes over the printing surface, the jets drop ink onto it, forming an image. The drop of ink is typically forced out of the jet or aperture by activation of an electromechanical transducer. The transducer receives an activation signal at the correct time, and it actuates to force the ink out of the apertures.
The drops then fall onto the printing substrate in a pattern determined by the activation signals received by the transducers, the patterns of the drop ultimately form the printed image. In some printers, the printing surface is the paper or other print surface that is the final surface upon which the image is formed. In other printers, the printing surface is an intermediate transfer surface, such as a drum or a belt, from which the image is then transferred to the final print surface. In either case, the timing of the activation of the jets determines the positions in which the drops fall on the printing surface.
In some printers, an effect exists that causes a subset of the jet array, such as the outer row or rows of jets, single jets, groups of jets in a particular area, edge jets, etc. to slow down over the initial months of use at operating temperatures. The velocity of the jet in its flight from the print head to the printing surface slows. Due to the movement between the printing surface and the jet array, this causes a drift in the dot position, degrading the overall print quality. This degradation or print quality may result in service calls because of fuzzy or blurred edges and lines in the printed images, requiring printhead replacement, or other action to remedy the issue.